Train order operation is a system by which the railroads of North America conveyed operating instructions before the days of centralized traffic control and use of track warrants conveyed by radio. Train order operation still exists on a few North American railroads, but has largely been replaced by more modern operating methods.

The term train order working is used in other regions of the world but the underlying details do not bear much similarity to North American methods of the past.

North American usage

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In what was termed timetable and train order operation, the operating timetable establishes scheduled trains and their class. Class is a way of establishing superiority (priority) between different trains (e.g., passenger, through freight, and local freight). On single track, the timetable specifies the points at which two trains would meet or pass. The timetable thus provides the basic framework for train movement on a particular portion of the railroad. However, variations in traffic levels from day to day, unforeseen delays, need to perform maintenance, and so forth dictates that a way be found to vary from the schedules established by the timetable.

The train order provides the means to deal with these changes in operating conditions as they arise. Orders modify the timetable. Among the functions a train order can perform are:

• creating a train not provided for by timetable (a so-called "extra").
• annulling a train provided by timetable.
• create sections of a schedule (in essence "cloning" a train's schedule and class when, for example, too much traffic exists to be handled by a single train).
• setting meeting points between extras since they have no timetable schedule.
• altering timetable meeting points (for example when one train is late and adhering to the timetable meeting point would cause delays for other trains).
• altering the schedule of a train to allow other trains to run with respect to the altered schedule rather than that given in the timetable.
• giving a train right over another train that ordinarily has timetable superiority.
• conveying warnings about temporary conditions such as temporary speed limits.

Train orders were issued by the train dispatcher responsible for the portion of railroad concerned. They were conveyed to telegraph operators at outlying stations along the railroad via telegraph or telephone; the receiving operator would copy the order onto onionskin forms designed for that purpose and would repeat the order back to the dispatcher so the latter could confirm correctness. After completing the order, it would then be delivered to all concerned trains either by hand (if the train stopped), or by delivery fork mounted at trackside for trains that did not stop. A train order signal was frequently provided to advise train and engine crews on passing trains whether orders were held for pickup.

The train and engine crews addressed by the order were obligated to observe the instructions provided in the train order, the details of which were provided by the operating rule book.

Explanation of train order depicted in image

Train order No. 115	Salem Yd, 11-2-1944	Specifies the order number, location issued (the dispatcher's office at the yard in Salem, Illinois) and date
To: C & E Exa 2005 Nth		Specifies the train(s) addressed and their location; in this case the order is addressed to "conductor and engineer of Extra 2005 North at VN Tower". Extra trains are designated by their engine number. Other trains affected by any order must receive a copy, which will be addressed at whatever location the order is to be delivered to those trains.
At: VN Tower
No 123 Eng 1001 take siding meet Extra 2005 North at Kell instead of Texico		Modifies the meet location specified in a previously-issued order and specifies which train takes siding at meeting point.
take siding meet No 174 Eng 895 and Extra 1937 North at Benton		Specifies another meet between No. 123 and two other trains, one scheduled and one extra; the engine number is specified for the scheduled train so that other trains can identify it by sight.
No 122 Eng 222 take siding meet No 123 Eng 1001 at Texico		Specifies another meet, this one between two scheduled trains and not directly concerning Extra 2005 North.
Made complete 659 am by RED		Time and call sign (initials) of the dispatcher issuing the order; once "made complete", the order becomes operative and continues so until fulfilled, superseded, or annulled.
Operator Cole		The name of the operator copying and repeating the order at VN Tower.

Use in other regions

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Train order working is a system of controlling the despatch of trains, especially on single lines, using telegraph messages.

On branch lines, these messages may be sent between the telegraph operators of the individual stations.

On busier lines, a central controller dispatches the necessary orders to the individual stations.

Rail transport in North America